During the last 20 years, a number of improvements have been taking place in controlling water chemistry in nuclear reactors and other vessels such as boilers and tanks in power plants and on ships, in a way to minimize corrosion and extend lifetime of the materials from which vessels, tanks and pipe lines are constructed. In the 1960's and 70's, and earlier, materials such as sodium hypo-sulfite (Na(H)So.sub.3) and bi-hydrogen phosphate, hydrozinc and other essentially hydrogen-rich oxygen "getters" were being added to waters with the primary purpose of providing free hydrogen to collect free oxygen that would otherwise cause corrosion (oxidation) of metallic components. In the 1970's and 1980's particularly in nuclear plants, water chemists began the introduction of gaseous hydrogen directly into the circulating water, this being made possible by economic considerations, and being desirable to eliminate various undesirable anions and cations introduced along with the hydrogen, when it had been added in relatively unstable chemical compounds. The excesses of free hydrogen also collect free oxygen produced radiologically by neutronic reactions that disassociate cooling water.
It has always been possible to meter the amounts of free hydrogen being added at a single point to systems containing many (sometimes hundreds) of tons of water. It has also been possible to draw samples from various points and measure by chromotography or wet analysis or spectrography how much hydrogen existed in the sample. It has not heretofore been possible, however, to measure exactly how much hydrogen actually existed in water deep inside the systems or vessels at the actual surfaces where corrosion was most damaging. The fuel surfaces in a nuclear reactor for example comprise about 14 acres of surface distributed among 47,000 pins, 12 feet long. Similar large, surface areas exist in steam generator and condensor tubes, where oxidation/corrosion reactions can occur.